1. Field of the Invention
The present invention relates to a process for preparing nitriles. More particularly, it relates to a process for producing a heteroaromatic nitrile comprising catalytically reacting an alkyl-substituted heteroaromatic compound with ammonia and molecular oxygen in a gaseous phase (namely, by ammoxidation).
The heteroaromatic nitriles are useful as starting materials in the preparation of medicines or agricultural chemicals.
2. Description of the Related Art
Japanese Patent Publication No. 19706/1982 and Japanese Patent Kokai Publication No. 156039/1982 disclose, as a catalyst for ammoxidation, a catalyst comprising antimony oxide, vanadium oxide and an oxide of a metal selected from the group consisting of iron, copper, titanium, cobalt, manganese and nickel. Although this catalyst has a comparatively high selectivity in case of a monoalkyl-substituted heteroaromatic compound, it tends to induce unfavorable reactions such as cleavage of a heteroaromatic ring in case of a dialkyl-substituted heteroaromatic compound so that the selectivity of the desired nitriles is decreased. In addition, this catalyst suffers from decrease of catalytic activity through reduction with ammonia and further its catalytic activity is largely decreased by deposition of carbon.